The present invention relates to a through capacitor used principally as a low-pass filter in various kinds of electric instrument, and in particular to a through capacitor which can prevent a lead terminal from separating and cracks from generating in a capacitor in the bending of the lead terminal.
FIG. 5 shows the conventional through capacitor generally known as a low-pass filter.
Referring now to FIG. 5, a through capacitor comprises a capacitor 3 having a di-, electric solid body 3' formed of, for example, ceramics or the like, in an almost cylindrical shape and provided with electrodes 1 and 2 formed on the internal periphery and the external periphery thereof, respectively, a lead terminal 6 axially passing through a through hole 4 provided in the internal electrode 1 and solder 5 for fixedly connecting the internal electrode 1 with the lead terminal 6.
The capacitor body 3, is provided with a tapered flange member 7 in the upper portion thereof, the internal electrode 1 being extended along the upper surface of the flange member 7, and the solder 5 for connecting the lead terminal 6 with the internal electrode 1 being piled up also on the flange portion 7 to form an expanded portion 5a.
The lead terminal 6 is provided with a projection 11 engaging with the upper portion side of the flange member 7, the projection 11 determining the position of the lead terminal 6 in relation to the capacitor 3, in addition, the projection 11 being buried in the expanded portion 5a of the solder 5 to fixedly connect the lead terminal 6 with the solder 5.
On the other hand, the external electrode 2 is extended along the lower surface of the flange member 7, the capacitor 3 being put in a circular opening 9 of a group plate 8 in a portion of the external electrode 2 and fixedly connected with the earth plate 8 by means of solder 10, and the flange member 7 determining the position of the capacitor 3 relative to the ground plate 8.
With a through capacitor having the above described construction, if an electric signal passes through the lead terminal 6, high-frequency noise components in the signal run into the ground plate 8 via the capacitor 3.
However, with the above described through capacitor, even though a downward tensile force and pressing force are given to the lead terminal 6, the lead terminal 6 can be prevented from or separating from the capacitor 3 due to the projection 11 and the expanded portion 5a of an solder 5 while if the upward tensile force and pressing force are given to the lead terminal 6, a problem occurs in that the internal elecrode 1 is comparatively easily separated from the capacitor 3 and the lead terminal 6 is separated from the capacitor 3.
It can be thought to overcome this problem by increasing the width of the capacitor 3 in the longitudinal direction of the lead terminal 6 to increase the contact area between the capacitor body 3 and the internal electrode 1. However, in such a case, a new disadvantage occurs in that a through capacitor is large-sized.
In addition, with the above described construction, as shown by a phantom line in FIG. 5, also the problem occurs in that a bent portion of the lead terminal 6 is brought into contact with the vicinity of the lower opened end 12 of the hole 4 of the capacitor 3 in the bending of the lead terminal 6, whereby cracks are apt to be generated in the capacitor 3.
Thus, it is an object of the present invention to provide a through capacitor in which a lead terminal is difficult to escape from a capacitor.
It is another object of the present invention to provide a through capacitor in which cracks are difficult to be generated on a capacitor in the bending of a lead terminal.